Method for ensuring symmetric audio quality for hands-free phoning

ABSTRACT

A hearing device includes a processor and a wireless transceiver operatively connected with the processor and configured to connect via a wireless link with a remote device and to exchange bi-directional audio packets with the remote device. The transmit power of the remote device is larger than the transmit power of the hearing device. The processor is configured to estimate the audio link packet error rate of the transmission via the wireless link, and generate a notification when the audio link packet error rate exceeds a pre-determined threshold.

FIELD OF INVENTION

The following description relates generally to a hearing system and amethod for operating a hearing system. More specifically, the followingdescription relates to transmit power control that ensures symmetricaudio link quality between a hearing device and a remote deviceconnected wirelessly to the hearing device.

BACKGROUND OF INVENTION

Advances in wireless technology allow wireless communications betweenhearing devices and remote devices. In such communications, at least oneremote device, such as a mobile phone, for example, transmits audiopackets, which are received by the hearing device. Due to size andbattery life limitations, hearing devices typically radiate wirelesssignals with a significantly smaller strength than typical audio sources(e.g., a smartphone). A hearing device usually transmits at a power of 0dBm. However, mobile phones transmit at a power of up to 20 dBm. Becausethe transmit powers of the hearing device and the mobile phone aresubstantially different (i.e., asymmetric), when the distance betweenthe hearing device and the mobile phone exceeds a certain range, thequality of the wireless link from the hearing device to the mobile phonedeteriorates and the quality of the transmitted audio deteriorates as aresult. It is desirable to avoid situations in which the quality of theaudio a hearing aid user receives is good, while the quality of theaudio received by a far-end user (i.e., another user interacting withthe hearing aid user by phone, for example) is bad. Such situationswhere the audio quality is asymmetric are referred to herein asasymmetric situations. It is desirable to provide control of thetransmission power by the hearing device to minimize the occurrence ofsuch asymmetric situations. It is further desirable to provide feedbackto the hearing aid user when such an asymmetric situation occurs.

SUMMARY

The present invention provides a hearing system that includes a hearingdevice and a remote device connected via a wireless link. Specifically,the present invention proposes solutions to implement notifications tothe user and automatic transmit power control to ensure symmetric audiolink quality when the transmit power of the remote device is larger thanthe transmit power of the hearing device.

In one general aspect, a hearing device may include a processor and awireless transceiver operatively connected with the processor. Thewireless transceiver may be configured to connect via a wireless linkwith at least one remote device and to exchange bi-directional audiopackets with the remote device. The transmit power of the remote devicemay be larger than the transmit power of the hearing device. Theprocessor may be configured to estimate an audio link packet error rateof a transmission via the wireless link, and generate a notification tothe hearing device user when the audio link packet error rate exceeds apre-determined threshold.

In the hearing device according to the foregoing aspect, the processormay be part of the wireless transceiver.

In the hearing device according to the foregoing aspect, the processormay be further configured to estimate an outgoing audio link packeterror rate.

In the hearing device according to the foregoing aspect, thenotification may include at least one of a single beep, a beep sequence,artificially degrading an incoming audio quality, or muting incomingaudio.

In the hearing device according to the foregoing aspect, the wirelesslink may follow the Bluetooth specification.

In the hearing device according to the foregoing aspect, the wirelesslink may follow the Hands-Free Profile (“HFP”) of the Bluetoothspecification.

In the hearing device according to the foregoing aspect, the wirelesslink may be configured to use the Enhanced Synchronousconnection-oriented (“eSCO”) transport option of the Bluetoothspecification or the isochronous transport option of the Bluetoothspecification.

In the hearing device according to the foregoing aspect, the audio linkpacket error rate may be estimated by monitoring a number of necessaryretransmissions from the hearing device towards the remote device.

In the hearing device according to the foregoing aspect, the audio linkpacket error rate may be estimated by monitoring acknowledgementstransmitted by the remote device related to audio packets received bythe remote device.

In another general aspect, a hearing device may include a processor anda wireless transceiver operatively connected with the processor. Thewireless transceiver may be configured to connect via a wireless linkwith at least one remote device and to exchange bi-directional audiopackets with the remote device. The processor may be configured tomonitor an audio link packet error rate and adapt the transmit power ofthe hearing device as a function of the audio link packet error rate.

In the hearing device according to the foregoing aspect, the processormay be part of the wireless transceiver.

In the hearing device according to the foregoing aspect, the remotedevice may be at least one of a mobile phone, a Digital EnhancedCordless Telecommunications (“DECT”) phone, a landline phone, a tablet,or a computer.

In the hearing device according to the foregoing aspect, the processormay be further configured to generate and send a notification when theaudio link packet error rate exceeds a pre-determined threshold.

In another general aspect, a method for controlling an audio quality ina hearing device including a processor and a wireless transceiveroperatively connected with the processor and configured to connect via awireless link with a remote device may include estimating an audio linkpacket error rate of a transmission via the wireless link and adaptingthe transmit power of the hearing device as a function of the audio linkpacket error rate.

In the method according to the foregoing aspect, the hearing device maybe configured to exchange bi-directional audio packets with the remotedevice via the wireless link.

In the method according to the foregoing aspect, the estimating theaudio link packet error rate may include monitoring a number ofnecessary retransmissions from the hearing device towards the remotedevice or monitoring acknowledgements transmitted by the remote devicerelated to audio packets received by the remote device from the hearingdevice.

In the method according to the foregoing aspect, the method forcontrolling an audio quality in a hearing device may further includegenerating and sending a notification when the audio link packet errorrate exceeds a pre-determined threshold.

In the method according to the foregoing aspect, the notification mayinclude at least one of a single beep, a beep sequence, artificiallydegrading an incoming audio quality, or muting incoming audio.

In another general aspect, a method for controlling an audio quality ina hearing device, including a processor and a wireless transceiveroperatively connected with the processor and configured to connect via awireless link with a remote device, may include estimating an audio linkpacket error rate of a transmission via the wireless link and generatingand sending a notification when the outgoing audio link packet errorrate exceeds a pre-determined threshold.

In the method according to the foregoing aspect, the notification mayinclude at least one of a single beep, a beep sequence, artificiallydegrading an incoming audio quality, or muting incoming audio.

Other features and aspects may be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other aspects of the present disclosure will becomeapparent to those skilled in the art to which the present disclosurerelates upon reading the following description with reference to theaccompanying drawings, in which:

FIG. 1 is a schematic diagram illustrating a hearing system with aremote device, an eavesdropper enabler hearing device (also calledparticipant hearing device), and an eavesdropper hearing device,according to an embodiment;

FIG. 2 is a schematic diagram illustrating an on-body (front or backpocket) and off-body use scenarios of the hearing system of FIG. 1;

FIG. 3 is a schematic diagram illustrating usage range zones withdifferent quality of the audio on the uplink and downlink of the hearingsystem of FIG. 1, according to an embodiment;

FIGS. 4A-4C are schematic diagrams illustrating quality of the audio andusage range zones depending on the location of the hearing system ofFIG. 1, according to an embodiment;

FIG. 5 is a schematic diagram illustrating audio link asymmetry of thehearing system of FIG. 1, according to an embodiment;

FIG. 6 is a flowchart illustrating a process of notifying the user ofthe hearing system of FIG. 1 of a bad audio link, according to anembodiment;

FIG. 7 is a flowchart illustrating a process of automatic control of thetransmit power of the hearing device in the hearing system of FIG. 1,according to an embodiment; and

FIG. 8 is a flowchart illustrating a combined process of notifying theuser of a bad audio link and automatic control of the transmit power ofthe hearing device, according to an embodiment.

Throughout the drawings and the detailed description, unless otherwisedescribed, the same drawing reference numerals will be understood torefer to the same elements, features, and structures. The relative sizeand depiction of these elements may be exaggerated for clarity,illustration, and convenience.

DETAILED DESCRIPTION

Example embodiments that incorporate one or more aspects of theapparatus and methodology are described and illustrated in the drawings.These illustrated examples are not intended to be a limitation on thepresent disclosure. For example, one or more aspects of the disclosedembodiments can be utilized in other embodiments and even other types ofdevices. Moreover, certain terminology is used herein for convenienceonly and is not to be taken as a limitation.

Within the context of the following description, hearing devices (suchas hearing aids, hearing prostheses, cochlear implants, earphones, etc.)are specifically utilized by individuals to hear audio from anotherdevice or from the user's surroundings and may be used, for example inorder to compensate hearing loss and/or improve hearing ability. A pairof hearing devices, one intended to be worn at the left and the other atthe right ear of the user, which are linked to one another is referredto as a binaural hearing system. Different styles of hearing devicesexist in the form of behind-the-ear (BTE), in-the-ear (ITE),completely-in-canal (CIC), or Invisible-in-the-Canal (ITC) types, aswell as hybrid designs consisting of an outside-the-ear part and anin-the-ear part, the latter typically including a receiver (i.e., aminiature loudspeaker), therefore commonly termed receiver-in-the-ear(RITE), receiver-in-canal (RIC), or canal-receiver-technology (CRT)hearing devices. Depending on the severity and/or cause of the user'shearing loss, other electro-mechanical output transducers, such as abone-anchored vibrator, a direct acoustic cochlear simulator (DACS) orcochlear implant (CI) can be employed instead of a receiver. Other usesof hearing devices pertain to augmenting the hearing of normal hearingpersons, for instance by means of noise suppression, to the provision ofaudio signals originating from remote sources, e.g., within the contextof audio communication, and for hearing protection.

Hearing devices with multiple separate units, such as one intended to beworn at the left and the other at the right ear of the user, forexample, allow communication between the two hearing device units, aswell as communication with other devices, such as a mobile phone or aportable audio player. This communication may take place via a remoteauxiliary unit, such as a hub, that acts as a communication relay.Advances in wireless technology allow direct wireless communicationsbetween a hearing device and remote devices, such as mobile phones(e.g., smartphone, such as iPhone, Android, Blackberry, etc.), DigitalEnhanced Cordless Telecommunications (“DECT”) phones, landline phones,tablets, media players (e.g., iPod, MP3 player, etc.), computers (e.g.,desktop or laptop, PC, Apple computer, etc.), audio/video (A/V)receivers that can be part of a home entertainment or home theatersystem, for example, a car audio system or circuitry within the car,remote control, an accessory electronic device, a wireless speaker, or asmart watch.

An example schematic diagram of such wireless communications system isillustrated in FIG. 1. The wireless communications system 10 can includea remote device 12 (illustrated as a mobile phone in FIG. 1, but notlimited thereto), a first hearing device 14, and a second hearing device16. However, embodiments are not limited thereto and otherconfigurations are contemplated. For example, the wirelesscommunications system 10 can include a remote device 12 and only onehearing device. In operation, the remote device 12 can wirelesslytransmit audio packets, which can be received by the first hearingdevice 14 and the second hearing device 16. The audio packets can betransmitted and received through wireless links using wirelesscommunication protocols, such as Bluetooth or WiFi® (based on the IEEE802.11 family of standards of the Institute of Electrical andElectronics Engineers), or the like, as well as other radio frequency(RF) communication protocols, for example. Among such point-to-pointwireless communications are protocols that conform to the Bluetoothspecification promulgated by the Bluetooth Special Interest Group ofBellevue, Wash. The Bluetooth Core Specification specifies both theBluetooth Classic variant of Bluetooth, also known as Bluetooth BasicRate/Enhanced Data Rate™ (Bluetooth BR/EDR™), as well as Bluetooth LowEnergy variant of Bluetooth, also known as Bluetooth LE, or BLE.Advances in integrated chip design have made it possible to develop achip that supports both Bluetooth Classic and Bluetooth Low Energy andthat has a size and a power consumption performance that is suitable forthe capabilities of hearing devices. Because Bluetooth BR/EDR™ isgenerally a point-to-point communication, it may be desirable for one oftwo hearing devices worn by a user to eavesdrop an audio stream to hearaudio in stereo while the other hearing device maintains apoint-to-point Bluetooth BR/EDR™ connection. Specifically, a primaryhearing device may establish a wireless connection with a remote deviceand begin streaming music, and a secondary audio device can eavesdropthe audio stream (e.g., without a wireless connection to the remotedevice). The primary hearing device can receive audio packets for theleft stereo channel and the secondary hearing device can eavesdrop audiopackets for the right stereo channel (or vice versa). Accordingly, A2DPeavesdropping allows the hearing device user to listen to an audiostream in stereo despite Bluetooth BR/EDR™ being a point-to-pointconnection.

In the Bluetooth system, when a hearing device is connected to a mobilephone, it is up to the mobile phone to control the transmit power of thehearing device. If the reception power is too low, the mobile phoneasks, via the Bluetooth protocol, to increase the transmit power of thehearing device. If the reception power is too high, the mobile phoneasks, via the Bluetooth protocol, to decrease the transmit power of thehearing device.

The Bluetooth system uses a closed loop power control. Each side can askthe other side to increase or decrease the transmitted power, with thegoal to receive the radio signal in the best power zone (e.g., not toweak and not too strong).

The first hearing device 14 and the second hearing device 16 can beelectro-acoustic transducers configured to convert audio informationinto sound. Such electro-acoustic transducers can include but are notlimited to earphones, ear buds, hearing aids, speakers, headphones,etc., for example. The first hearing device 14 may be configured as aleft channel speaker for a stereo channel and the second hearing device16 may be configured as a right channel speaker for a stereo channel, orvice-versa.

As shown in FIG. 1, each of the first hearing device 14 and the secondhearing device 16 can include an input microphone system 18′, 18″configured to capture an audio signal and convert the audio signal intoan electrical input signal. Although the microphone system shown in FIG.1 includes only one input microphone 18′, 18″, the microphone system caninclude more than one input microphone. The microphone 18′, 18″ may bedirectional, i.e., may pick up most sounds in front a person wearing themicrophone, or omnidirectional, i.e., may pick up sounds from alldirections. In addition to the input microphone 18′, 18″, furtherreceiving means for receiving signals may be present, such as a telecoilreceiver, a receiving unit including an antenna for receiving wirelesslytransmitted signals, etc. For example, a streamed audio input signal(such as a phone call or music) can be received from a streaming inputsource, such as the remote device 12, for example, by a wirelessconnection, such as wireless point-to-point link 20, for example.

The electrical input signals obtained from the input microphone 18′, 18″can be processed by a signal processor 22′, 22″ that can convert theelectrical input signals into digital signals that can be processedfurther to obtain an electrical output signal. A desired electricalinput signal can be the electrical input signal obtained by the inputmicrophone 18′, 18″, the streamed audio input signal, or a mix of bothinput signals. The electrical output signal can be converted into anacoustic output signal by a receiver 24′, 24″ (also known as a“speaker”) and can be emitted into the remaining volume between theuser's eardrum and the earpiece or the in-the-ear-canal-component of thehearing device.

The signal processor 22′, 22″ may be a single digital signal processoror may be made up of different, potentially distributed processor units,preferably including at least one digital signal processor unit. Thesignal processor 22′, 22″ can include one or more of a microprocessor, amicrocontroller, a digital signal processor (DSP), an applicationspecific integrated circuit (ASIC), a field-programmable gate array(FPGA), discrete logic circuitry, or the like, appropriately programmedwith software and/or computer code, or a combination of special purposehardware and programmable circuitry. The signal processor 22′, 22″ maybe further adapted to differentiate sounds, such as speech andbackground noise, and process the sounds differently for a seamlesshearing experience. The signal processor 22′, 22″ can further supportcancellation of feedback or noise from wind, ambient disturbances, etc.

The signal processor 22′, 22″ can further include memory (not shown inFIG. 1) and may store tables with pre-determined values, ranges, andthresholds, as well as program instructions that may cause the signalprocessor 22′, 22″ to access the memory, execute the programinstructions, and provide the functionality ascribed to it herein. Thememory may include one or more volatile, non-volatile, magnetic,optical, or electrical media, such as read-only memory (ROM), randomaccess memory (RAM), electrically-erasable programmable ROM (EEPROM),flash memory, or the like. The signal processor 22′, 22″ can furtherinclude one or more analog-to-digital (A/D) and digital-to-analog (D/A)converters for converting various analog inputs to the signal processor22′, 22″, such as analog input from the microphone 18′, 18″, forexample, in digital signals and for converting various digital outputsfrom the signal processor 22′, 22″ to analog signals representingaudible sound data which can be applied to the speaker 24′, 24″, forexample.

Each of the first hearing device 14 and the second hearing device 16 canbe configured to wirelessly receive audio or other signals from eachother, from the remote device 12, or from another device, component orsystem, such as a remote hearing device controller, a hearing loopsystem, an audio link device, or a streaming device, for example. Eachof the first hearing device 14 and the second hearing device 16 caninclude a wireless communication unit, such as a transceiver 26′, 26″configured to receive and optionally to transmit wireless signals toother devices. For example, each of the first hearing device 14 and thesecond hearing device 16 may receive wireless audio signals and/orcontrol signals from a remote device via an antenna 25′, 25″, and conveythem to the signal processor 22′, 22″ or to each other. In certainembodiments, the transceiver 26′, 26″ may be a part of the signalprocessor 22′, 22″. Specifically, the signal processor 22′, 22″ canemploy a Bluetooth receiver, an audio codec that provides the audiosignal conveyed by a remote device, such as the remote device 12, forexample, in digitized form, and a decoder that decodes the digitizedaudio signal. Alternatively, the transceiver 26′, 26″ may include itsown Bluetooth on-board signal processor 23. As illustrated in FIG. 1,the transceiver 26′ can include a transmit counter (txCnt) 27 and areceive counter (rxCnt) 29, which may count how many attempts haveoccurred to transmit and receive an audio packet between the firsthearing device 14 and the remote device. The transceiver 26′ can alsoinclude a power amplifier 31 that may be configured to amplify thesignal from the microphone 18′. The transceiver 26′ can further includea controller 32 that can receive the respective counts from the transmitcounter (txCnt) and the receive counter (rxCnt), send a control signalto the amplifier to amplify an audio signal, or send notifications tothe first hearing device 14 and the second hearing device 16 regardingthe quality of the wireless link 20 based on the counts from thetransmit counter (txCnt) and the receive counter (rxCnt), as describedbelow. The controller 32 may be a single digital signal processor or mayinclude one or more of a microprocessor, a microcontroller, a digitalsignal processor (DSP), an application specific integrated circuit(ASIC), a field-programmable gate array (FPGA), discrete logiccircuitry, a memory, or the like. The transceiver 26″ can have a similarconfiguration, particularly if the roles of the hearings devices 14 and16 are reversed, and the second hearing device 16 performs the functionsof a participant/eavesdropper enabler.

Modern hearing devices can be used to make and receive telephone callsand stream audio using a remote device, such as mobile phone, via awireless link, using a bi-directional hands-free profile. This link canalso be used for voice communication with a digital assistant on themobile phone. The mobile phone can be worn by the user on-body (e.g., ina front pocket, back-pocket, or in a bag), or off-body (e.g., on a tableor desk), as illustrated in FIG. 2. A hearing device usually transmitsat a power of 0 dBm. At the same time, current mobile phones maytransmit at a power of up to 20 dBm and the power level increases witheach new generation of mobile phones. Because the transmit powers of thehearing device and the mobile phone are different (e.g., asymmetric),when the distance between the hearing device and the mobile phoneexceeds a certain range, the wireless link quality can deteriorate andthe quality of the transmitted audio can deteriorate as a result. Forexample, as illustrated in FIG. 3, certain range zones can result ingood audio for both the uplink (e.g., the wireless link from the hearingdevice to the mobile phone) and downlink (e.g., the wireless link fromthe mobile phone to the hearing device) (user 301), in good audio on thedownlink only and bad audio on the uplink (user 302), and with bad audioon both the uplink and downlink (user 303). These differences betweenthe uplink and the downlink in the situations shown for user 302, forexample, can cause wireless link asymmetry that can result in bad audioon the uplink and/or the downlink (i.e., on the bad wireless link). Inthe worst case scenario, the Bluetooth link may be completely lost (user304).

In addition, even if mobile phone is worn by the user on-body, thelocation of the mobile phone can still affect the wireless link, asillustrated in FIGS. 4A-4C. For example, when the mobile phone is wornby the user in the front pocket, the link quality remains acceptable(FIG. 4A). When the mobile phone is worn by the user in the back pocket,the link quality depends on the position of the user's arms.Specifically, when the mobile phone is worn by the user in the backpocket and the user's arms are up or away from the user's body, the linkquality remains acceptable (FIG. 4B). However, when the mobile phone isworn by the user in the back pocket and the user's arms are down orclose to the user's body, the link quality deteriorates (FIG. 4C).

Some hearing devices are susceptible to wireless link asymmetry due tothe different (e.g., asymmetric) transmit powers of the hearing deviceand the mobile phone, when the distance between the hearing device andthe mobile phone exceeds a certain range. The amount of link asymmetrycan be calculated with the following formula:A=(PhoneTxPower−HearingAidSensitivity)−(HearingAidTxPower−PhoneSensitivity)=(20−(−91))−(0−(−91))=20, where the value −91 dBm forthe sensitivity of the hearing aid and of the mobile phone is a typicalsensitivity for Bluetooth chips. The wireless link asymmetry isillustrated in FIG. 5. The hearing system described herein can controlautomatically (e.g., without manual intervention by the user) anyasymmetry of the wireless links between the hearing device and theremote device, thereby improving the audio quality.

Turning back to FIG. 1, it may be desirable to transmit the sound comingfrom the mobile phone 12 into both ears of the user. The first (e.g.,left) hearing device 14 can be connected to the remote device 12 via thewireless point-to-point link 20, which can conform to the Bluetoothprotocol. A separate Bluetooth or a proprietary wireless link 28 may beformed between the first hearing device 14 and the second hearing device16 for network management purposes and/or to coordinate actions betweenthe first hearing device 14 and the second hearing device 16 concerningaudio received from the remote device 12, for example. The first hearingdevice 14 can receive audio packets directly from the remote device 12via the wireless link 20. The second (e.g., right) hearing device 16 canbe configured to eavesdrop on (that is, can listen in on or observe) theBluetooth link 20 between the mobile phone 12 and the first hearingdevice 14 to also receive the audio packets sent from the remote device12 by picking up the audio sent by the mobile phone 12 to the firsthearing device 14 and playing back this sound. For example, the secondhearing device 16 can be configured to eavesdrop on the Bluetooth link20 between the mobile phone 12 and the first hearing device 14 via acommunication link 30. In other words, the first hearing device 14 canbe configured as a participant or an eavesdropper enabler (EDE) and thesecond hearing device 16 can be configured as an eavesdropper (ED). Theeavesdropper and participant roles are not necessarily limited to thesecond hearing device 16 and the first hearing device 14, as illustratedin FIG. 1, and can be reversed. For example, the first (left) hearingdevice 14 could be the eavesdropper and the second (right) hearingdevice 16 could be the participant.

The Hands-Free Profile (“HFP”) and the Advanced Audio DistributionProfile (“A2DP”) of the Bluetooth specification may both be utilized forthe point-to-point links 20 and 28. When HFP is utilized, the remotedevice 12 can send incoming audio to the first hearing device 14. Thefirst hearing device 14 renders the received incoming audio. The secondhearing device 16 can eavesdrop the mono (i.e., monaural) incoming audiolink and also renders the received incoming audio. When A2DP isutilized, the first hearing device 14 receives a stereo (i.e.,stereophonic) signal and renders only the left audio channel. The secondhearing device 16 can eavesdrop on the stereo signal and render theright audio channel.

The first hearing device 14 can be configured to transmit an outgoingaudio packet (e.g., voice for a telephone call or voice commands toapplications stored on the mobile phone 12) to the mobile phone 12. Theoutgoing audio packet can be transmitted via the wireless point-to-pointlink 20, which conforms to a wireless communication protocol such asBluetooth BR/EDR™, Bluetooth Low Energy™, a proprietary communication(e.g., binaural communication protocol between hearing aids or bimodalcommunication protocol between a hearing aid and hearing device),ZigBee™, Wi-Fi™, or an Industry of Electrical and Electronic Engineers(IEEE) wireless communication standard (e.g., 802.11), for example. Thewireless link 20 may also be configured for bi-directionalcommunications allowing transmission and receipt of audio packets, aswell as transmission and receipt of acknowledgements (ACK) by thehearing devices 14, 16 that an audio packet was successfully received,for example. The wireless link 20 may further be configured forbi-directional communications between the first hearing device 14 andthe mobile phone 12, allowing not only transmission and receipt of audiopackets between the first hearing device 14 and the remote device 12,but also acknowledgements by the mobile phone 12 that an audio packetfrom the first hearing device 14 was successfully received. Thebi-directional link 20 can minimize the number of audio packetre-transmissions when an audio packet has been received and noretransmission is necessary. When an audio packet from the remote device12 is not received or is received corrupted by the first hearing device14, the first hearing device 14 can transmit an error signal across thewireless link 20 to the remote device 12 to request retransmission ofthe audio packet. Such an error signal is called a negative acknowledge(NAK) in the Bluetooth specification, in opposition to the positiveacknowledge (ACK). When an audio packet from the first hearing device 14is not received or is received corrupted by the remote device 12, theremote device 12 can transmit an error signal across the wireless link20 to the first hearing device 14 to request retransmission of the audiopacket. When an audio packet is not received or is received corrupted bythe second hearing device 16, the second hearing device 16 can transmitan error signal via the separate wireless link 28 to the first hearingdevice 14 to be forwarded to the remote device across the wireless link20 requesting retransmission of the audio packet.

When an audio packet is not received or is received corrupted by themobile phone 12, the mobile phone 12 can transmit an error signal acrossthe wireless link 20 to the first hearing device 14 to requestretransmission of the audio packet.

In a point-to-point protocol, a packet is formatted in 8-bit bytes, andcan include control information and data, which is also known as thepayload. Control information can provide data for delivering thepayload, such as source and destination network addresses, errordetection codes, and sequencing information, for example. Typically,control information can be found in the packet header. An audio packetcan be considered corrupted if at least one bit is erroneous. In digitaltransmission, the number of bit errors is the number of received bits ofa data stream over a communication channel that has been altered due tonoise, interference, distortion, or bit synchronization errors. A packeterror rate (PER) (also known as packet error rate) of a transmission viathe point-to-point protocol (e.g., the wireless link) is the number ofincorrectly received data packets divided by the total number ofreceived packets. The packet error rate (PER) is used to test andmeasure the performance of a receiver.

Because the transmit powers of the first hearing device 14 and themobile phone 12 are different (e.g., asymmetric), when the distancebetween the first hearing device 14 and the mobile phone 12 exceeds acertain range, the quality of the wireless link 20 can deteriorate. As aresult of the deteriorated quality of the wireless link 20, the audiopackets transmitted from the first hearing device 14 to the mobile phone12 can be corrupted or not received at all, and the quality of the audiotransmitted from the first hearing device 14 to the mobile phone 12 candeteriorate. It may be desirable to notify the user of the hearingdevice of the deteriorated quality of the wireless link and to controlthe transmit power of the hearing device when a wireless link withdeteriorated quality is detected.

In one embodiment, the hearing system 10 can be configured to notify theuser about wireless link asymmetry when a bad audio state is detected.

As discussed above, the transceiver 26′, 26″ of the first hearing device14 and the second hearing device 16, respectively, may include its ownBluetooth on-board signal processor 23. In this embodiment, theprocessor 23 of the transceiver 26′ of the first hearing device 14 canbe configured to measure or estimate the outgoing packet error rate(PerTx) on the wireless link 20 between the first hearing device 14 andthe mobile phone 12. Alternatively, the processor 22′ of the firsthearing device 14 can be configured to measure or estimate the outgoingpacket error rate (PerTx). As yet another alternative, the outgoingpacket error rate (PerTx) on the wireless link 20 can be estimated by aprocessor of the mobile phone 12. The PerTx measurement is performed onthe hearing device that is connected bi-directionally with the mobilephone 12. In the example illustrated in FIG. 1, the hearing device thatis connected bi-directionally with the mobile phone 12 is the firsthearing device 14. Specifically, when the hearing device 14 is connectedto the mobile phone 12, the processor 23 of the transceiver 26′ can beconfigured to compute the outgoing packet error rate PerTx by monitoringthe number of the retransmissions from the first hearing device 14towards the mobile phone 12. Retransmissions from the first hearingdevice 14 towards the mobile phone 12 are performed when an audio packetfrom the first hearing device 14 is not received or is receivedcorrupted by the remote device 12. In this situation, the remote device12 can transmit an error signal across the wireless link 20 to the firsthearing device 14 to request retransmission of the audio packet.Alternatively, because the wireless link 20 may be configured fortransmission of acknowledgements by the mobile phone 12 that an audiopacket from the first hearing device 14 was successfully received, thefirst hearing device 14 may retransmit the audio packet to the remotedevice when the first hearing device 14 has not received anacknowledgment from the mobile phone 12 of a successful receipt of theaudio packet.

As illustrated in FIG. 6, in Step 1, the processor 23 of the transceiver26′ measures the outgoing packet error rate PerTx.

In Step 2, the processor 23 of the transceiver 26′ checks whether theoutgoing packet error rate PerTx is above a threshold T4 (“badthreshold”). When the outgoing packet error rate PerTx is above acertain threshold, the quality of the audio link has deteriorated to thepoint that the audio is not understandable and the wireless link isconsidered bad. The audio error rate above which audio is notunderstandable is typically around 20%, but may vary depending oncontext. A Bluetooth Hands-Free Profile (“HFP”) audio link may beconfigured to use two or three transmit attempts NT. Sometimes, even ifa wireless link is negotiated by the mobile phone to use three transmitsattempts, the third transmit attempt may not be listened to by themobile phone. Therefore, typically only two transmit attempts areavailable even if the link allows for a third transmit.

With a Modified SBC Codec (mSBC) for Bluetooth devices, at 1 Mbps, oneaudio frame of 7.5 ms is transmitted in two radio packets. The AverageFrame Error Rate (FER) can be calculated with the formula:FER=1−(1−PER^N_(T))^2.

With a Continuously variable slope delta modulation (CVSD), at 1 Mbps,one audio frame of 3.75 ms is transmitted in one radio packet. TheAverage Frame Error Rate (FER) can be calculated with the formula:FER=PER^N_(T), where PER is the outgoing packet error rate PerTx.

Assuming that the audio error rate above which audio is notunderstandable is 20%, the bad audio state can be entered if theoutgoing packet error rate PerTx is above 1−(1−0.2)^(1/2))^(1/2)=32% and(1−(1−0.2)^(1/2))^(1/3)=47% with two and three transmit attempts,respectively. Considering the case of two transmit attempts, the badaudio threshold T4 can preferably be chosen at T4=0.32.

Turning back to FIG. 6, in Step 3, if the outgoing packet error ratePerTx is above the threshold T4, the processor 22′ starts generating abad audio warning to the user. Alternatively, the bad audio warning maybe generated by the processor 23 of the transceiver 26′. As yet anotheralternative, the bad audio warning may be generated by the processor ofthe mobile phone 12.

In Step 4, if the outgoing packet error rate PerTx is not above thethreshold T4, the processor 23 of the transceiver 26′ measures again theoutgoing packet error rate PerTx in Step 1.

The bad audio warning can be a notification to the user of the badoutgoing audio link by playing one or more warning beeps (e.g., a beepsequence), artificially degrading the incoming audio link quality, ormuting the incoming audio. Degrading the incoming audio link quality maybe achieved for example via dropping a certain percentage (such as 20%,for example) of incoming audio packet. The goal of all of these warningsis to notify the user that the wireless link 20 is weak, which shouldprompt the user to bring the mobile phone 12 closer to the hearingdevice 14. The beep notification can be explicit, while the degradingand/or muting the incoming audio link quality can be intuitive. Althoughthe PerTx measurement is made on the hearing device that is connectedbi-directionally with the mobile phone (e.g., the first hearing device14), the notification about bad audio state can be made on both hearingdevices, for example, by using a message transmitted via the wirelesslink 28 between the first and the second hearing devices that triggersthe notification (as shown in FIG. 1). The bad audio notification ispreferably applied during the entire time when the outgoing audio linkis assumed to be in the bad audio state. Alternatively, the warning,especially if it is a beep sequence, may be generated only when enteringthe bad audio state.

In Step 5, during bad audio state, the processor 23 of the transceiver26′ measures again the outgoing packet error rate PerTx, and in Step 6,the processor 23 of the transceiver 26′ checks whether the outgoingpacket error rate PerTx is below another threshold T3 (the “goodthreshold”), which is lower than the threshold T4. If the outgoingpacket error rate PerTx is below the good audio threshold T3, in Step 7the processor 23 of the transceiver 26′ resumes normal audio playback.

The value of the good audio threshold T3 can be chosen sufficientlybelow the bad audio threshold T4 to avoid rapid toggling between goodand bad audio. At 20% outgoing packet error rate PerTx, the audio errorrate is 1−(1−0.2^2)^2=7.8% with two transmits and 1−(1−0.2^3)^2=1.6%with three transmits. At 7.8% audio error rate, the audio isunderstandable and a good audio state can be entered. Accordingly, thepresent embodiment can select T3 to be 20%.

In Step 8, when the outgoing packet error rate PerTx is not below thethreshold T3, the process continues with the processor 23 of thetransceiver 26′ measuring again the outgoing packet error rate PerTx inStep 5.

In another embodiment, the hearing system 10 can be configured toautomatically adapt the transmitted power of the hearing device as afunction of the outgoing audio link packet error rate.

The conducted transmit power is the transmit power that a radiofrequency (RF) transmitter (e.g., radio chip) produces at its output orthe transmit power of the radio chip measured when a power meter isconnected to the radio chip in place of the antenna. The effectiveradiated power (ERP) or the effective isotropic radiated power (EIRP),also known as a radiated power, is the effective power produced at theoutput of the radio chip including the ability of the antenna to directthat power in a certain direction or in the direction of the antenna'sstrongest beam, respectively. The conducted transmit power is relevantfor link asymmetry, since the effect of the antenna is symmetric on boththe transmit and receive paths.

In the present embodiment, the hearing device can decide autonomouslywhether to use a higher or a lower transmit power. This embodiment hasthe advantage of minimizing the power consumption in the hearing devicevia using a lower transmit power whenever possible.

As illustrated in FIG. 7, in Step 1, the processor 23 of the transceiver26′ measures the outgoing packet error rate PerTx.

In Step 2, the processor 23 of the transceiver 26′ checks whether theoutgoing packet error rate PerTx is above a threshold T2.

In Step 3, if the outgoing packet error rate PerTx is above thethreshold T2, the processor 23 of the transceiver 26′ enters a high RFoutput power state.

In Step 4, if the outgoing packet error rate PerTx is not above thethreshold T2, the processor 23 of the transceiver 26′ measures again theoutgoing packet error rate PerTx in Step 1.

In Step 5, during the high RF output power state, the processor 23 ofthe transceiver 26′ measures again the outgoing packet error rate PerTx,and in Step 6, the processor 23 of the transceiver 26′ checks whetherthe outgoing packet error rate PerTx is below another threshold T1,which is lower than the threshold T2. If the outgoing packet error ratePerTx is below the threshold T1, in Step 7 the processor 23 of thetransceiver 26′ enters the low RF output power state.

In Step 8, when the outgoing packet error rate PerTx is not below thethreshold T1, the process continues with the processor 23 of thetransceiver 26′ measuring again the outgoing packet error rate PerTx inStep 5.

The process illustrated in FIG. 7 can be seen as a two-step regulationloop.

The thresholds T1 and T2 can determine the usage or non-usage of thehigh transmit power mode. T1 and T2 can preferably be selected such thatthe audio quality stays good. Accordingly, T2 can be preferably selectedto be smaller than T3, with a value for T2 of 15%, for example.

T1 can be selected to be smaller than T2, preferably with a value for T1of 5%.

A variation of the embodiment illustrated in FIG. 7 could be for theprocessor 23 of the transceiver 26′ to select a transmit power that iscomputed using a fine grain regulation loop algorithm that increases ordecreases the transmit power, such as to reach a target value for thelink quality metric.

Another embodiment is a combination of the two embodiments describedabove and illustrated in FIGS. 6 and 7.

As illustrated in FIG. 8, in Step 1, the transceiver 26′ measures theoutgoing packet error rate PerTx.

In Step 2, the transceiver 26′ checks whether the outgoing packet errorrate PerTx is above a threshold T2.

In Step 3, if the outgoing packet error rate PerTx is above thethreshold T2, the processor 23 of the transceiver 26′ enters a high RFoutput power state.

In Step 4, if the outgoing packet error rate PerTx is not above thethreshold T2, the processor 23 of the transceiver 26′ measures again theoutgoing packet error rate PerTx in Step 1.

In Step 5, during the high RF output power state, the processor 23 ofthe transceiver 26′ measures again the outgoing packet error rate PerTx,and in Step 6, the processor 23 of the transceiver 26′ checks whetherthe outgoing packet error rate PerTx is below a threshold T1, which islower than the threshold T2. If the outgoing packet error rate PerTx isbelow the threshold T1, in Step 7 the processor 23 of the transceiver26′ enters the low RF output power state.

In Step 8, when the outgoing packet error rate PerTx is not below thethreshold T1, the process continues in Step 9 with the processor 23 ofthe transceiver 26′ checking whether the outgoing packet error ratePerTx is above T4.

In Step 11, if the outgoing packet error rate PerTx is not above thethreshold T4 (e.g., if the outgoing packet error rate PerTx is below orequal to the threshold T4), the process continues with the processor 23of the transceiver 26′ measuring again the outgoing packet error ratePerTx in Step 5 and follows the same steps described above.

In Step 10, if the outgoing packet error rate PerTx is above thresholdT4, the processor 22′ starts generating a bad audio warning to the user.Alternatively, the bad audio warning may be generated by the processor23 of the transceiver 26′. The processor 23 of the transceiver 26′ thenmeasures again the outgoing packet error rate PerTx in Step 12 and inStep 13, checks whether the outgoing packet error rate PerTx is belowanother threshold T3 (good audio threshold), which is lower than the badaudio threshold T4. If the outgoing packet error rate PerTx is below thegood audio threshold T3, in Step 14 the processor 23 of the transceiver26′ resumes normal audio playback. Because in Step 14, the RF power isstill high the process continues with the processor 23 of thetransceiver 26′ measuring again the outgoing packet error rate PerTx inStep 5 and follows the same steps described above.

In Step 15, when the outgoing packet error rate PerTx is not below thethreshold T3, the process continues with the processor 23 of thetransceiver 26′ measuring again the outgoing packet error rate PerTx inStep 12.

The bad audio warning can be either a notification to the user of thebad outgoing audio link by playing one or more warning beeps (e.g., abeep sequence), or artificially degrading the incoming audio linkquality, or muting the incoming audio. The goal of all of these warningsis to notify the user that the wireless link 20 is weak, which shouldprompt the user to bring the mobile phone 12 closer to the hearingdevice 14. The beep notification can be explicit, while the degradingand/or muting the incoming audio link quality can be intuitive. Althoughthe PerTx measurement is made on the hearing device that is connectedbi-directionally with the mobile phone (e.g., the first hearing device14), the notification about bad audio state can be made on both hearingdevices, for example, by using a message transmitted via the wirelesslink 28 between the first and the second hearing devices that triggersthe notification (as shown in FIG. 1).

The thresholds T1, T2, T3, and T4 can be selected in the same mannerdescribed above with reference to the embodiments illustrated in FIGS. 6and 7, with preferably the following values respectively, 5%, 15%, 20%and 32%.

The methods of the embodiments described above applies to an EnhancedSynchronous connection-oriented (“eSCO”) link or a wireless link thatuses the eSCO transport option of the Bluetooth specification. WithSynchronous connection-oriented (“SCO”) links (e.g., where each devicetransmits encoded voice data in a reserved timeslot or a reserved frame,without retransmits), it may not be possible to reliably estimate thetransmit Tx link quality. Enhanced SCO (eSCO) links allow greaterflexibility in that they may use retransmissions to achieve reliability,allow a wider variety of packet types, and greater intervals betweenpackets than SCO, thus increasing radio availability for other links.

In this embodiment, the PerTx estimation can be based only on the firsttransmit attempt of every eSCO frame, and can include the followingsteps:

At the establishment of an eSCO link, the processor 23 of thetransceiver 26′ can set the following values for the outgoing packeterror rate PerTx and the bad HFP transmit link:

PerTx=0

hfpTxLinkBad=0

After every eSCO frame (i.e., every 3.75 ms), the processor 23 of thetransceiver 26′ can retrieve transmit count (txCnt) and receive count(rxCnt), which indicate how many attempts have occurred to transmit andreceive an audio frame, respectively.

The processor 23 of the transceiver 26′ can then check whether no headerhas been received or both rxCnt and txCnt are>1 (i.e., whether neitherthe first reception nor the first transmit attempt was successful):

If true (i.e., no header has been received or both rxCnt and txCntare >1), the processor 23 of the transceiver 26′ can set the value forthe transmit error txError to 1.

If false, the processor 23 of the transceiver 26′ can set txError to 1if txCnt>1 (i.e., the first transmit attempt was not successful) or to 0otherwise.

The processor 23 of the transceiver 26′ can then update PerTx using theformula PerTx=min((1−1/256)*PerTx+1/256*txError; T4)

The value PerTx can be saturated at the threshold value T4 via thefunction min(X; T4), such that the time needed to reach the good audiostate when the link is good again is fixed.

The methods of the embodiments described above can apply to a wirelesslink that uses the isochronous transport option of the Bluetoothspecification. For certain communication links, only a limited amount ofdelay is allowed and retransmissions are allowed up to a certain limitat which the current payload must be disregarded and the next payloadmust be considered. This data transfer is known as isochronous traffic.In other words, the retransmit process must be overruled in order tocontinue with the next data payload. Aborting the retransmit scheme canbe accomplished by flushing the old data and forcing the Bluetoothcontroller to take the next data instead.

The packet error rate estimate PerTx can be implemented using anexponential moving speed average according to the formulaPerTx(k)=(1−a)* PerTx(k−1)+a*txError, where “a” is the degree ofweighting decrease; and txError takes the value 1 if a transmittedpacket is observed to have been lost and the value 0 if a transmittedpacket is observed to have been received. The variable “a” sets themoving average speed. This parameter can be chosen as a trade-offbetween speed of bad link detection and accuracy of measurement. Thevalue a=1/256 can be selected to provide a detection time that is closeto one second, but not exceeding one second. This selection can providethe highest accuracy while not being too slow. FIGS. 12a-12c illustratethree plots with a=1/1286, 1/256 and 1/512, respectively. The blacklines show the estimated PER. The yellow line shows the theoreticalaverage PER. A time 0, the PER is increased from PER1=10% to PER2=50%(blue lines). The yellow line cross the T4 threshold (red line) at time0.38 s, 0.77 s and 1.53 s for a=1/128, 1/256 and 1/512 respectively.

In certain embodiments, the audio link quality may be estimated viaReceived Signal Strength Indicator (“RSSI”). Specifically, instead ofkeeping statistics of the effective errors on the outgoing audio link,the signal strength of the incoming audio link can be measured and theexpected audio link quality can be deduced on the outgoing link.

Other embodiments can monitor the incoming audio link. For example, theincoming audio quality may be monitored via packet error statistics. Anotification can be transmitted to the user when the audio quality isbad in either or in both the incoming and outgoing directions.

Many other example embodiments can be provided through variouscombinations of the above described features. Although the embodimentsdescribed hereinabove use specific examples and alternatives, it will beunderstood by those skilled in the art that various additionalalternatives may be used and equivalents may be substituted for elementsand/or steps described herein, without necessarily deviating from theintended scope of the application. Modifications may be desirable toadapt the embodiments to a particular situation or to particular needswithout departing from the intended scope of the application. It isintended that the application not be limited to the particular exampleimplementations and example embodiments described herein, but that theclaims be given their broadest reasonable interpretation to cover allnovel and non-obvious embodiments, literal or equivalent, disclosed ornot, covered thereby.

What is claimed is:
 1. A hearing device comprising: a processor; and awireless transceiver operatively connected with the processor, thewireless transceiver being configured to connect via a wireless linkwith at least one remote device, and being configured to exchangebi-directional audio packets with the remote device, wherein: a transmitpower of the remote device is larger than a transmit power of thehearing device, and the processor is configured to: estimate an audiolink packet error rate of a transmission via the wireless link, andgenerate a notification to the hearing device user when the audio linkpacket error rate exceeds a pre-determined threshold.
 2. The hearingdevice according to claim 1, wherein the processor is part of thewireless transceiver.
 3. The hearing device according to claim 1,wherein the processor is further configured to estimate an outgoingaudio link packet error rate.
 4. The hearing device according to claim1, wherein the notification comprises at least one of a single beep, abeep sequence, artificially degrading an incoming audio quality, ormuting incoming audio.
 5. The hearing device according to claim 1,wherein the wireless link follows a Bluetooth specification.
 6. Thehearing device according to claim 5, wherein the wireless link follows aHands-Free Profile (“HFP”) of the Bluetooth specification.
 7. Thehearing device according to claim 5, wherein the wireless link isconfigured to use an Enhanced Synchronous connection-oriented (“eSCO”)transport option of the Bluetooth specification or an isochronoustransport option of the Bluetooth specification.
 8. The hearing deviceaccording to claim 1, wherein the audio link packet error rate isestimated by monitoring a number of necessary retransmissions from thehearing device towards the remote device.
 9. The hearing deviceaccording to claim 1, wherein the audio link packet error rate isestimated by monitoring acknowledgements transmitted by the remotedevice related to audio packets received by the remote device.
 10. Ahearing device comprising: a processor; and a wireless transceiveroperatively connected with the processor, the wireless transceiver beingconfigured to connect via a wireless link with at least one remotedevice, and being configured to exchange bi-directional audio packetswith the remote device, wherein: the processor is configured to: monitoran audio link packet error rate, and adapt a transmit power of thehearing device as a function of the audio link packet error rate. 11.The hearing device according to claim 10, wherein the processor is partof the wireless transceiver.
 12. The hearing device according to claim10, wherein the remote device is at least one of a mobile phone, aDigital Enhanced Cordless Telecommunications (“DECT”) phone, a landlinephone, a tablet, or a computer.
 13. The hearing device according toclaim 10, wherein the processor is further configured to generate andsend a notification when the audio link packet error rate exceeds apre-determined threshold.
 14. A method for controlling an audio qualityin a hearing device comprising a processor and a wireless transceiveroperatively connected with the processor, the wireless transceiver beingconfigured to connect via a wireless link with a remote device, themethod comprising: estimating an audio link packet error rate of atransmission via the wireless link, and adapting a transmit power of thehearing device as a function of the audio link packet error rate. 15.The method according to claim 14, wherein the hearing device isconfigured to exchange bi-directional audio packets with the remotedevice via the wireless link.
 16. The method according to claim 14,wherein estimating the audio link packet error rate comprises monitoringa number of necessary retransmissions from the hearing device towardsthe remote device or monitoring acknowledgements transmitted by theremote device related to audio packets received by the remote devicefrom the hearing device.
 17. The method according to claim 14, furthercomprising: generating and sending a notification when the audio linkpacket error rate exceeds a pre-determined threshold.
 18. The methodaccording to claim 17, wherein the notification comprises at least oneof a single beep, a beep sequence, artificially degrading an incomingaudio quality, or muting incoming audio.
 19. A method for controlling anaudio quality in a hearing device comprising a processor and a wirelesstransceiver operatively connected with the processor, the wirelesstransceiver being configured to connect via a wireless link with aremote device, the method comprising: estimating an outgoing audio linkpacket error rate of a transmission via the wireless link, andgenerating and sending a notification when the outgoing audio linkpacket error rate exceeds a pre-determined threshold.
 20. The methodaccording to claim 19, wherein the notification comprises at least oneof a single beep, a beep sequence, artificially degrading an incomingaudio quality, or muting incoming audio.